Trim and tilt mechanism for outboard propulsion unit

ABSTRACT

A trim and tilt mechanism for an outboard motor comprising a short stroke hydraulic cylinder acting against the outboard motor at a relatively long moment arm to accomplish trimming of the motor against the resistance of the propeller thrust, and a long stroke hydraulic cylinder acting at a relatively short moment arm to accomplish rapid upward tilting movement of the unit to its fully raised position.

United States Patent 1 1 3,581,702

[72] Inventor Theodore J. Moberg [56] References Cited UNITED STATESPATENTS gmfi ig 2.930.730 5/1960 Patty. .lr. 115/41(Xl [45] PatentedJude 1971 2.997.014 8/1961 Puckett 115/17 [73] Assignee ChryslerCorporation 3.191.573 6/1965 HlXOl'l 115/41 Highland Park Mich 3.406.65210/1968 MettetaLJr. 115/41 3.460.505 8/1969 Thoene 115/17 3,250,2405/1966 Ziegler 115/17 Primary Examiner-Milt0n Buchler AssistantExaminer-Carl A. Rutledge Attorney-Harness, Talburtt & Baldwin [54] TRIMAND TILT MECHAMSM FOR OUTBOARD ABSTRACT: A trim and tilt mechanism foran outboard P S motor comprising a short stroke hydraulic cylinderacting 1 rawmg against the outboard motor at a relatively long momentarm to [52] US. Cl 115/41 accomplish trimming of the motor against theresistance of the [51] Int. Cl B63h 5/12 propeller thrust, and a longstroke hydraulic cylinder acting at [50] Field of Search 115/41,41 arelatively short moment arm to accomplish rapid upward HT. 17 tiltingmovement of the unit to its fully raised position.

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TRIM AND TILT MECHANISM FOR OUTBOARD PROPULSION UNIT BACKGROUND OFINVENTION This invention relates to power lift devices for outboardpropulsion units and, more particularly, to a combined trim and tiltmechanism for outboard propulsion units. Outboard propulsion units arearranged to pivot upward about a generally horizontal axis between aworking position in which the propeller is in the water and a raisedposition in which the propeller is out of the water. The first or lowerportion of this movement in which the propeller remains in the water andmerely undergoes an adjustment in its angle or trim may be referred toas the tirm" portion of its upward pivotal movement and the subsequentportion of this movement in which the propeller is moved clear of thewater and pivoted upwardly to its fully raised position may be referredto as the tilt portionof the upward pivotal movement. The problems andrequirements of moving an outboard propulsion unit through the trimportion of its upward lifting movement are distinctly different from theproblems and requirements of moving the unit through the tilt portion ofits upward pivotal movement. Many lift mechanisms have been proposedand/or are presently available for outboard propulsion units but none ofthese prior art units completely recognizes and successfully copes withall of the unique problems and requirements of the two distinct rangesof upward pivotal movement.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a combined trim and tilt mechanism for outboard propulsionunits.

A more specific object is to provide a combined trim and tilt mechanismfor outboard propulsion units which recognizes and satisfies all of theperformance requirements unique to the distinct stages of upward pivotalmovement of the unit.

According to one feature of the present invention, the motor lift meansfor the propulsion unit operates to move the unit at a relatively slowangular speed through the trim range, whereby to allow fine adjustmentof the trim of the propeller, and at a relatively fast angular speedthrough the tilt range whereby to allow the unit to be quickly moved toits fully raised position.

According to a further feature, the motor lift means acts on thepropulsion unit through a relatively long moment arm during movementthrough the trim range, whereby to successfully overcome the highpropeller thrust load during forward movement of the boat, and acts onthe propulsion unit through a relatively short moment arm duringmovement through the tilt range, whereby to provide a large amount ofupward angular movement of the unit for each increment of movement ofthe motor lift means.

According to another feature of the invention, the motor lift meanscomprises fluid motor means, and means are provided for selectivelyvarying the effective working area of the fluid motor means as thepropulsion unit is pivoted about its axis.

In the disclosed embodiment, a short stroke. hydraulic cylinder ispositioned to act against the propulsion unit at a location remote fromthe axis of pivotal movement of the unit, whereby to develop a highforce acting through a long moment arm, and a long stroke hydrauliccylinder is positioned to act against the propulsion unit at a locationrelatively close to the pivot axis, whereby to provide a long tiltstroke acting through a short moment arm to provide rapid angularmovement of the unit to its fully raised position.

Other features and advantages of the invention will be apparent from thedetailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiment of theinvention is illustrated in the accompanying drawings, in which:

FIG. 1 is a partially fragmentary view of auboat equipped with anoutboard propulsion unit employing a trim and tilt mechanism accordingto the invention;

FIG. 2 is a cross-sectional view taken on line 2-2 of FIG. 1;

FIGS. 3 and 4 are partially schematic views showing moved positions ofthe outboard propulsion unit; and

FIG. 5 is a fragmentary view looking in the direction of the arrow 5 inFIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The outboard propulsionunit seen in the drawings is of the outboard motor type; that is, anoutboard propulsion unit in which the power source for the unit isdisposed outboard of the vessel to be propelled. Although the inventionis described in detail with reference to an outboard motor, it will beunderstood that the trim and tilt mechanism of the invention is equallyapplicable to outboard propulsion units of the stem drive orinboard-outboard type in which the power source is located inboard ofthe vessel to be propelled.

The outboard motor 10 seen in the drawings includes a cowl 12 housing anengine (not shown), a hollow drive shaft housing 14 enclosing a driveshaft (not shown), an anticavitation plate 16, a gear housing or lowerunit 18, and a propeller 20. A swivel pin 22 is carried at the forwardedge of drive shaft housing 14. Outboard motor 10 is shown in thedrawings mounted on a boat 24 having a transom 26. Motor 10 is removablymounted on transom 26 by a pair of stem brackets 28, 30 and a swivelbracket 32. The near stern bracket 28 is removed in FIGS. 3 and 4 forclarity of illustration.

Stem brackets 28, 30 are C-shaped in cross section and are held in aclamped position over transom 26 by clamp screws 34 having screw plates36 engaging the inboard face 38 of transom 26; clamp screws 34 areturned by screw handles 40. Stern brackets 28, 30 are mounted on transom26 in transversely spaced relation with a pivot shaft 42 extendingbetween and interconnecting the spaced brackets.

Swivel bracket 32 is generally of inverted L configuration and includesa forwardly extending leg portion 43 terminating in a horizontal journalportion 44 joumaled on pivot shaft 42, and a downwardly extending legportion 45 including a central journal portion 46 journaling motorswivel pin 22. Swivel bracket 32 also includes sidewalls 47 whichreinforce leg portions 43, 45. The near sidewall 47 is removed in FIGS.1, 3 and 4 for clarity of illustration.

The described bracket arrangement enables outboard motor 10 to pivotwith swivel bracket 32 upwardly about the axis of pivot shaft 42, orswivel independently of swivel bracket 32 about the axis of swivel pin22.

Outboard motor 10 is provided with a combination trim and tilt mechanismconsisting of a trim cylinder 48, a tilt cylinder 50, a pressure fluidsource 52, and a control device 54.

Trim cylinder 48 is a relatively large bore, relatively short strokehydraulic cylinder of the double acting or two-way type. The tubularouter shell or casing 48a of trim cylinder 48 is rigidly secured to amounting member 56 and member 56 is rigidly secured to the outboard face58 of transom 26. Alternatively, mounting plate 56 may be attached to,or'fonned integrally with, stern brackets 28, 30. The free end 481) ofthe piston rod 48c of trim cylinder 48 has bearing engagement with theforward face 60a of a block 60 formed as an integral forward extensionof the lower end of swivel pin journal portion 46 of swivel bracket 32.Trim cylinder 48 will be seen to be arranged to extend generally normalto a line passing through the axis of shaft 42 and through piston rodtip 48c so that its line of action is generally in direct opposition tothe line of action of the thrust force generated by propeller 20 duringforward movement of the boat. Trim cylinder 48 may, for example, have abore of 2.00 inches and a stroke of 1.75.

Tilt cylinder 50 is a relatively small bore, relatively long strokehydraulic cylinder of the double acting or two-way type. The lower endof the tubular outer shell of casing 501: of tilt cylinder 50 ispivotally connected to the lower end of stem bracket 30 by a pivot pin61. The free or upper end 50b of the piston rod 500 of tilt cylinder 50is pivotally connected by a pivot pin 62 to 3 lug 63 formed as a forwardextension of theupper end of the swivel bracket sidewall 47 adjacentstern bracket 30. Tilt cylinder 50 may be provided with a pair of op'positely oriented relief valves (not shown, but of known form) in itspiston so that pressure fluid may flow through one relief valve from thelower to the upper end of the cylinder in the event that the fluidpressure in the lower end of the cylinder builds up to a predeterminedvalue, or may flow in the reverse direction through the other reliefvalve if pressure in the upper end of the cylinder becomes excessive.Tilt cylinder 50 may, for example, have a bore of 1.38 inches, and astroke of 3.30 inches and may be of the type available from EltraCorporation ofToledo, Ohio as Part No. 105275.

Pressure fluid source 52 comprises a motor-pump unit consisting of areversible constant speed electric motor 64 driving a reversiblepositive displacement pump 65 of the type including a built-in sump.Pump 65 is designed to deliver a substantially constant volume of fluidunder the constant speed drive of motor 64 with the pressure of thedelivered fluid varying with variations in the load placed on the pump.Motor 64 and pump 65 may be mounted on a plate 66 secured to thestarboard face of the outboard portion of stem bracket 28. Motorpumpunit 64, 65 may, for example, by of the type available from EltraCorporation of Toledo, Ohio as Part No. 104208.

A hydraulic conduit 68 connects with pump port 650 and divides intoconduits 68a, 68b communicating, respectively, with the forward end oftrim cylinder 48 and the lower end of tilt cylinder 50. Anotherhydraulic conduit 70 connects with pump port 65b and is divided intoconduits 70a, 70b communicating, respectively, with the rearward end oftrim cylinder 48 and the upper end of tilt cylinder 50.

Control device 54 is preferably positioned forwardly in the boatadjacent the operator's seat and consists of a switching unit of knownform. Switching unit 54 includes pushbuttons 54a and 54b. Pushbutton54a, when depressed, establishes electrical communication betweenstorage battery 72 and motor 64 in a sense to drive motor 64 and pump 65in a direction to supply pressure fluid through conduit 68 and establisha fluid return path through conduit 70. Pushbutton 54b, when depressed,establishes an electrical circuit of opposite polarity to motor 64 todrive pump 65 in a direction to supply pressure fluid through conduit 70and establish a return path through conduit 68.

OPERATION OF THE PREFERRED EMBODIMENT Outboard motor unit will normallybe in the down position of FIG. 1 during operation. If the operatordesires to vary the trim" of the motor, button 54a may be depressed;this actuates pump 65 in a sense to simultaneously extend may thusreadily move the outboard motor within the small range 48 and 50 andpivot motor 10 about axis 42. The work load during this trimmingmovement of the outboard motor is borne almost entirely by the trimcylinder; the trim cylinder is able to move the outboard motor readily,however, even during conditions of high propeller thrust occurringduring rapid forward movement of the boat, since the working area of thetrim cylinder is large thereby allowing the cylinder to generate a largeforce with a relatively low fluid pressure, and the moment arm of thetrim cylinder is relatively long. Trim cylinder 48 of working positionsbetween the solid line full down position of FIG. 1 and the full trimposition of FIG. 3. This working range of Him position is shownbracketed in FIG. 1. During this movement within the trim range, thepressure fluid output of pump 65 is split between large bore trimcylinder 48 and small bore trim cylinder 50 so that the extension ofthese cylinders is relatively slow and positive, thereby allowing finecalibration or adjustment of the outboard motor within the trim range.As the outboard motor reaches its full trim position, trim cylinder 48runs out of stroke so that any further upward tilting movement of theoutboard motor must be accomplished solely by tilt cylinder 50. As tiltcylinder 50 is extended beyond the full trim position, the outboardmotor is moved through the off-plane positions seen in FIG. 1 (in whichthe propeller is still in the water but is beyond the full trimposition) and then upwardly out of the water toward the full tiltposition of FIG. 4. Since tilt cylinder 50 is connected to the swivelbracket at a location much closer to tilt axis 42 than the point ofbearing engagement of trim cylinder 48 with the swivel bracket, the tiltcylinder is able to move the propeller through a relatively large tiltare as the tilt cylinder is extended. Further, since the entire outputof pump 65 is now being delivered to relatively small bore cylinder 50,this cylinder extends relatively rapidly so that the movement of theoutboard motor unit within the off-plane and tilt range is relativelyrapid as compared to its deliberate, finely adjustable movement withinthe trim range. The speed of angular movement of the outboard motor unitwithin the off-plane and tilt range is also augmented by the shortmoment arm of the tilt cylinder which has the effect of producing arelatively large angular movement of the propeller for each increment ofextension of the tilt cylinder. The pressure developed in the fluidcircuit during movement of the motor unit through its offplane and tiltranges will depend on the load encountered. The circuit pressure in anyevent will have to increase as the trim cylinder runs out of stroke andthe tilt cylinder takes over the movement of the outboard motor unit,since the effective working area of the fluid motor means being suppliedby the pump is now significantly decreased, thereby requiring a highercircuit pressure to develop a given lifting force, and since the momentarm through which this force is being applied is now significantlyshortened, thereby requiring a larger force to counterbalance andmovingly overcome the gravity weight load of the unit and/or the thrustforce developed by the propeller. With the propeller positioned by tiltcylinder 50 in any of its off-plane positions, the outboard motor unitmay be operated under low power in shallow water situations, such asbeaching, without risking harm to the lower end of the outboard unit. Ifa high propeller thrust force is being developed as the motor unit movesinto its off-plane range from its trim range, the circuit pressure mayquickly build up to the pressure setting of the relief valves in thepiston of the tilt cylinder in which event the tilt cylinder will shortcircuit itself through one of the relief valves and the outboard motorunit will refuse to pivot upwardly beyond its full trim position.Barring this extreme conditions, however, the circuit pressure willincrease as the tilt cylinder takes over to a value to overcome thegravity and/or thrust load of the unit and the outboard motor unit willbe moved upwardly through the off-plane and tilt positions at asignificantly increased angular speed as compared to the relatively slowangular speed at which it was moved within the trim range. cylinder inthe event that excessive propeller thrust is generated with thepropeller in one of its off-plane positions; this bypassing actionallows the cylinder to contract to return the motor to its full trimposition where the trim cylinder picks up and successfully resists thepropeller thrust to prevent further downward pivotal movement of themotor. The relief valve arrangement in the tilt cylinder also functionsto bypass fluid from the upper to the lower end of the tilt cylinder inthe event that the lower end of the outboard motor unit strikes anobstacle, thereby allowing the outboard unit to pivot upwardly about pin42 to prevent damage to the outboard unit. Since pump 65 is of thepositive displacement type in the particular embodiment disclosed, motor10 will hold in any pivotal position to which it is moved either withinthe lower trim range, the off-plane range or the upper tilt range.

The motor may be moved downwardly (or counterclockwise as viewed inFIG, 1) from any position ofpivotal adjustment by depressing button 54b.Downward movement of the unit is accomplished in a positive manner bythe delivery of pressure fluid to the outer end of trim cylinder 48 andthe upper end of tilt cylinder 50 and the exhausting of fluid from thelower end of the cylinder 50 and the inner end of trim cylinder 48. Trimcylinder 50 retracts first; tilt cylinder 48 remaining extended untilcontacted by the outboard motor.

The invention trim and tilt mechanism will be seen to provide a simple,unitary system which may be readily applied to any outboard propulsionunit and which when thus applied, provides a positive, strong and finelyadjustable movement of the propulsion unit in the trim range whileproviding a rapid, expedient movement of the unit in its tilt range.

While a preferred embodiment of the invention has been illustrated anddescribed in detail, it will be apparent that various changes andmodifications may be made in the proposed embodiment without departingfrom the scope or spirit of the invention.

lclaim:

1. In an outboard marine propulsion unit adapted to be positionedrearwardly of the transom of the boat to be propelled in a normallydownwardly oriented position with the propeller at the lower end of theunit disposed in wetted position below the water line, and beingpivotally movable relative to said transom about a generally horizontalaxis upwardly through a range of wetted trim positions and thereafterthrough a range of tilt positions in which the propeller is raised outof the water, the improvement comprising a combined trim and tilt meansincluding motor means connected to said propulsion unit for pivotallymoving the latter upwardly about said axis, operative during themovement of said unit through said trim range to move said unit at arelatively slow angular speed and operative during the movement of saidunit through said tilt range to move said unit at a relatively fastangular speed.

2. In an outboard marine propulsion unit adapted to be positionedrearwardly of the transom of the boat to be propelled in a normallydownwardly oriented position with the propeller at the lower end of theunit disposed in wetted position below the water line, and beingpivotally movable relative to said transom about a generally horizontalaxis upwardly through a range of wetted trim positions and thereafterthrough a range of tilt positions in which the propeller is raised outof the water, the improvement comprising combined trim and tilt meansincluding motor means operative during the upward movement of said unitthrough said trim range to apply a pivoting force to said unit having arelatively long moment arm and operative during the upward movement ofsaid unit through said tilt range to apply a pivoting force to said unithaving a relatively short moment arm.

3. An outboard propulsion system according to claim 2 wherein said motormeans includes A. first motor means operative during said trim rangemovement and acting through said relatively long moment arm; and

B. second motor means operative during said tilt range movement andacting through said relatively short moment arm.

4. In an outboard marine propulsion unit adapted to be positionedrearwardly of the transom of the boat to be propelled and beingpivotally movable relative to said transom about a generally horizontalaxis between a working position in which the propeller at the lower endof the propulsion unit is disposed below the water line to providepropulsion for the boat and a raised position in which the propeller israised out of the water, the improvement comprising a trim and tiltmechanism for said propulsion unit including A. fluid motor meansconnected to said propulsion unit for pivotally moving the latter aboutsaid axis;

B. a source of pressure fluid;

C. means for delivering pressure fluid from said source to said motormeans; and

D. means for varying the effective working area of said fluid motormeans as said propulsion unit is moved about said axis by said fluidmotor means.

5. An outboard propulsion unit according to claim 4 wherein A. saidmotor means includes first and second fluid motors;

and

B. said delivery means includes means for routing pressure fluid to saidfirst motor means during the initial portion of the upward movement ofsaid unit from said working position and routing pressure fluid to saidsecond motor means during the subsequent portion of said upwardmovement.

6. An outboard propulsion unit according to claim 5 wherein:

C. said delivery means is operative to route pressure fluid to both ofsaid motor means during said initial movement portion and is operativeto route pressure fluid only to said second motor means during saidsubsequent movement portion.

7. An outboard propulsion unit according to claim 5 wherein:

C. said first motor means has a relatively large working area and saidsecond motor means has a relatively small working area.

8. An outboard propulsion unit according to claim 5 wherein C. saidfirst motor means acts on said propulsion unit through a relatively longmoment arm and said second motor means acts through a relatively shortmoment arm.

9. In an outboard marine propulsion unit adapted to be positionedrearwardly of the transom of the boat to be propelled and beingpivotally movable relative to said transom about a generally horizontalaxis between a working position in which the propeller at the lower endof the propulsion unit is disposed below the water line to providepropulsion for the boat and a raised position in which the propeller israised out of the water, the improvement comprising a trim and tiltmechanism for said propulsion unit including A. a relatively shortstroke hydraulic trim cylinder having engagement at one end with saidtransom or with a member rigid with said transom and having engagementat its other end with said propulsion unit or with a member pivotallymovable about said axis with said unit, said trim cylinder having astroke only long enough to move said propulsion unit from its workingposition to an intermediate angular position between said workingposition and said raised position; and

B. a relatively long stroke hydraulic tilt cylinder having engagement atone end with said transom or with a member rigid with said transom andhaving engagement at its other end with said propulsion unit or with amember pivotally movable about said axis with said unit, said tiltcylinder having a stroke long enough to pivotally move said propulsionunit from intermediate position to said raised position.

10. An outboard propulsion unit according to claim 9 wherein E. the lineof action of said relatively short stroke cylinder with said propulsionunit in said working position is angularly displaced from the line ofaction of said relatively long stroke cylinder.

11. In an outboard marine propulsion unit adaptedto be positionedrearwardly of the transom of the boat to be propelled and beingpivotally movable relative to said transom about a generally horizontalaxis between a working position in which the propeller at the lower endof the propulsion unit is disposed below the water line to providepropulsion for the board and a raised position in which the propeller israised out of the water; the improvement comprising a trim and tiltmechanism for said propulsion unit including A. a first hydrauliccylinder having engagement at one end with said transom or with a memberrigid with said transom and having engagement at its other end with saidpropulsion unit or with a member pivotally movable about said axis withsaid unit;

B. a second hydraulic cylinder having engagement at one end with saidtransom or with a member rigid with said transom and having engagementat its other end with said propulsion unit or with a member pivotallymovable about said axis with said unit, the line of action of said firstcylinder with said propulsion unit in said working position beingangularly displaced from the line of action of said second cylinder withsaid propulsion unit in said working position.

l2. An outboard propulsion unit according to claim 11 wherein D. saidfirst cylinder is a relatively short stroke trim cylinder and saidsecond cylinder is a relatively long stroke tilt cylinder.

13. An outboard propulsion unit according to claim 12 wherein E. theline of action of said trim cylinder with said propulsion unit in itsworking position is closer to the horizontal than the line of action ofsaid tilt cylinder.

14. An outboard propulsion unit according to claim 13 wherein F. theline of action of said trim cylinder with said propulsion unit in itsworking position is generally horizontal; and

G. the line of action of said tilt cylinder with said propulsion unit inits working position is generally vertical.

15. In an outboard marine propulsion unit adapted to be positionedrearwardly of the transom of the boat to be propelled and beingpivotally movable relative to said transom about a generally horizontalaxis between a small angular range of working positions in which thepropeller at the lower end of the propulsion unit is disposed below thewater line to provide propulsion for the boat and a raised position inwhich the propeller is raised out of the water, the improvementcomprising a trim and tilt mechanism for said propulsion unit includingA. a relatively short stroke hydraulic trim cylinder connected at oneend to said transom or to a member rigid with said transom and bearingat its other end against a surface (n said propulsion unit or on amember pivotally movable about said axis with said unit, said trimcylinder having a stroke only long enough to move said propulsion unitwithin said small angular range of working positions and having a lineof action generally opposing the line of action of the thrust forcegenerated by said propeller so as to enable the cylinder to effectivelyovercome the propeller thrust when thus trimming the propulsion unit;and

B. a relatively long stroke hydraulic tilt cylinder connected at one endto said transom or to a member rigid with said transom and connected atits other end to said propulsion unit or with a member pivotally movableabout said axis with said unit, the connection of said tilt cylinder tosaid propulsion unit being located closer to said pivot axis than thepoint of bearing engagement of said trim cylinder with said propulsionunit so as to maximize the tilting action of said tilt cylinder andenable it to move said propulsion unit all the way to its raisedposition.

16. An outboard marine propulsion unit according to claim 15 and furtherincluding C. a source of pressure fluid; and

D. means for routing pressure fluid simultaneously to said trim and tiltcylinders from said pressure fluid source to effect conjoint extensionof said cylinders during the initial portion of the upward pivotalmovement of said propulsion unit and thereafter, after said trimcylinder has reached the end of its stroke, to effect further extensionof said tilt cylinder to move said propulsion unit surface away fromsaid trim cylinder other end and move said propulsion unit to its raisedposition.

Disclaimer 3,581,702.The0do're J. Moberg, Hartford, Wis. TRIM AND TILTMECHA- NISM FOR OUTBOARD PROPULSION UNIT. Patent dated June 1, 1971.Disclaimer filed Feb. 10, 1972, by the assignee, Chrysler Corporation.Hereby enters this disclaimer to claims 1 through 16, inclusive, of saidpatent.

[Ofiicz'al Gazette July 25, 1972.]

1. In an outboard marine propulsion unit adapted to be positionedrearwardly of the transom of the boat to be propelled in a normallydownwardly oriented position with the propeller at the lower end of theunit disposed in wetted position below the water line, and beingpivotally movable relative to said transom about a generally horizontalaxis upwardly through a range of wetted trim positions and thereafterthrough a range of tilt positions in which the propeller is raised outof the water, the improvement comprising a combined trim and tilt meansincluding motor means connected to said propulsion unit for pivotallymoving the latter upwardly about said axis, operative during themovement of said unit through said trim range to move said unit at arelatively slow angular speed and operative during the movement of saidunit through said tilt range to move said unit at a relatively fastangular speed.
 2. In an outboard marine propulsion unit adapted to bepositioned rearwardly of the transom of the boat to be propelled in anormally downwardly oriented position with the propeller at the lowerend of the unit disposed in wetted position below the water line, andbeing pivotally movable relative to said transom about a generallyhorizontal axis upwardly through a range of wetted trim positions andthereafter through a range of tilt positions in which the propeller israised out of the water, the improvement comprising combined trim andtilt means including motor means operative during the upward movement ofsaid unit through said trim range to apply a pivoting force to said unithaving a relatively long moment arm and operative during the upwardmovement of said unit through said tilt range to apply a pivoting forceto said unit having a relatively short moment arm.
 3. An outboardpropulsion system according to claim 2 wherein said motor means includesA. first motor means operative during said trim range movement andacting through said relatively long moment arm; and B. second motormeans operative during said tilt range movement and acting through saidrelatively short moment arm.
 4. In an outboard marine propulsion unitadapted to be positioned rearwardly of the transom of the boat to bepropelled and being pivotally movable relative to said transom about agenerally horizontal axis between a working position in which thepropeller at the lower end of the propulsion unit is disposed below thewater line to provide propulsion for the boat and a raised position inwhich the propeller is raised out of the water, the improvementcomprising a trim and tilt mechanism for said propulsion unit includingA. fluid motor means connected to said propulsion unit for pivotallymoving the latter about said axis; B. a source of pressure fluid; C.means for delivering pressure fluid from said source to said motormeans; and D. means for varying the effective working area of said fluidmotor means as said propulsion unit is moved about said axis by saidfluid motor means.
 5. An outboard propulsion unit according to claim 4wherein A. said motor means includes first and second fluid motors; andB. said delivery means includes means for routing pressure fluid to saidfirst motor means during the initial portion of the upward movement ofsaid unit from said working position and routing pressure fluid to saidsecond motor means during the subsequent portion of said upwardmovement.
 6. An outboard propulsion unit according to claim 5 wherein:C. said delivery means is operative to route pressure fluid to both ofsaid motor means during said initial movement portion and is operativeto route pressure fluid only to said second motor means during saidsubsequent movement portion.
 7. An outboard propulsion unit according toclaim 5 wherein: C. said first motor means has a relatively largeworking area and said second motor means has a relatively small workingarea.
 8. An outboard propulsion unit according to claim 5 wherein C.said first motor means acts on said propulsion unit through a relativelylong moment arm and said second motor means acts through a relativelyshort moment arm.
 9. In an outboard marine propulsion unit adapted to bepositioned rearwardly of the transom of the boat to be propelled andbeing pivotally movable relative to said transom about a generallyhorizontal axis between a working position in which the propeller at thelower end of the propulsion unit is disposed below the water line toprovide propulsion for the boat and a raised position in which thepropeller is raised out of the water, the improvement comprising a trimand tilt mechanism for said propulsion unit including A. a relativelyshort stroke hydraulic trim cylinder having engagement at one end withsaid transom or with a member rigid with said transom and havingengagement at its other end with said propulsion unit or with a memberpivotally movable about said axis with said unit, said trim cylinderhaving a stroke only long enough to move said propulsion unit from itsworking position to an intermediate angular position between saidworking position and said raised position; and B. a relatively longstroke hydraulic tilt cylinder having engagement at one end with saidtransom or with a member rigid with said transom and having engagementat its other end with said propulsion unit or with a member pivotallymovable about said axis witH said unit, said tilt cylinder having astroke long enough to pivotally move said propulsion unit fromintermediate position to said raised position.
 10. An outboardpropulsion unit according to claim 9 wherein E. the line of action ofsaid relatively short stroke cylinder with said propulsion unit in saidworking position is angularly displaced from the line of action of saidrelatively long stroke cylinder.
 11. In an outboard marine propulsionunit adapted to be positioned rearwardly of the transom of the boat tobe propelled and being pivotally movable relative to said transom abouta generally horizontal axis between a working position in which thepropeller at the lower end of the propulsion unit is disposed below thewater line to provide propulsion for the board and a raised position inwhich the propeller is raised out of the water; the improvementcomprising a trim and tilt mechanism for said propulsion unit includingA. a first hydraulic cylinder having engagement at one end with saidtransom or with a member rigid with said transom and having engagementat its other end with said propulsion unit or with a member pivotallymovable about said axis with said unit; B. a second hydraulic cylinderhaving engagement at one end with said transom or with a member rigidwith said transom and having engagement at its other end with saidpropulsion unit or with a member pivotally movable about said axis withsaid unit, the line of action of said first cylinder with saidpropulsion unit in said working position being angularly displaced fromthe line of action of said second cylinder with said propulsion unit insaid working position.
 12. An outboard propulsion unit according toclaim 11 wherein D. said first cylinder is a relatively short stroketrim cylinder and said second cylinder is a relatively long stroke tiltcylinder.
 13. An outboard propulsion unit according to claim 12 whereinE. the line of action of said trim cylinder with said propulsion unit inits working position is closer to the horizontal than the line of actionof said tilt cylinder.
 14. An outboard propulsion unit according toclaim 13 wherein F. the line of action of said trim cylinder with saidpropulsion unit in its working position is generally horizontal; and G.the line of action of said tilt cylinder with said propulsion unit inits working position is generally vertical.
 15. In an outboard marinepropulsion unit adapted to be positioned rearwardly of the transom ofthe boat to be propelled and being pivotally movable relative to saidtransom about a generally horizontal axis between a small angular rangeof working positions in which the propeller at the lower end of thepropulsion unit is disposed below the water line to provide propulsionfor the boat and a raised position in which the propeller is raised outof the water, the improvement comprising a trim and tilt mechanism forsaid propulsion unit including A. a relatively short stroke hydraulictrim cylinder connected at one end to said transom or to a member rigidwith said transom and bearing at its other end against a surface on saidpropulsion unit or on a member pivotally movable about said axis withsaid unit, said trim cylinder having a stroke only long enough to movesaid propulsion unit within said small angular range of workingpositions and having a line of action generally opposing the line ofaction of the thrust force generated by said propeller so as to enablethe cylinder to effectively overcome the propeller thrust when thustrimming the propulsion unit; and B. a relatively long stroke hydraulictilt cylinder connected at one end to said transom or to a member rigidwith said transom and connected at its other end to said propulsion unitor with a member pivotally movable about said axis with said unit, theconnection of said tilt cylinder to said propulsion unit being locatedcloser to said pivot axis than the point of bearing engagement of saiDtrim cylinder with said propulsion unit so as to maximize the tiltingaction of said tilt cylinder and enable it to move said propulsion unitall the way to its raised position.
 16. An outboard marine propulsionunit according to claim 15 and further including C. a source of pressurefluid; and D. means for routing pressure fluid simultaneously to saidtrim and tilt cylinders from said pressure fluid source to effectconjoint extension of said cylinders during the initial portion of theupward pivotal movement of said propulsion unit and thereafter, aftersaid trim cylinder has reached the end of its stroke, to effect furtherextension of said tilt cylinder to move said propulsion unit surfaceaway from said trim cylinder other end and move said propulsion unit toits raised position.